Method and means for operating an ink jet printer without splatter

ABSTRACT

In an ink drop printer, an impacting drop may cause spatter which acts as a fog settling over various parts of the machine and printer media. The drops are maintained intact by directing a flow of gas to intercept only the terminating portion of the path of said ink drops just prior to and at the time of impacting upon a region of paper and to cover the region of said paper upon which the ink drops fall, whereby the deleterious effects of spatter may be eliminated.

United States Patent 1191 Kent et a1.

[54] METHOD AND MEANS FOR OPERATING AN INK JET PRINTER WITHOUT sRLATTER [75] Inventors: Robert I. Keur, Niles; Henry A.

Dahl, Mt. Prospect, both of I11.

73 Assignee': A. B. Dick Company, Chicago, 111.

22 Filed; Dec. 29, 1972 21 Appl. NO.: 319,909

[52] US. Cl. 101/42 6, lOl/DIG. l3, 346/1,

[51] Int. Cl. (301d 15/18 [58] Field of Search 101/1, DIG. 13, 416, 417,

118/6371'117/37 LE, 37 R;-178/6.6 R

[56] References Cited UNITED STATES PATENTS 2,577,894 12/1951 Jacob 346 75 2,676,868 4/1954 "Jacob 346/75 2,842,053 7/1958 De Marchi 101/416 R 3,011,435 12/1961 Jones et al..... 101 1310. 13 3,298,030 l/l967 Lewis et a1 346/75 3,363,545 H1968 Johnson et a1.. IOIIDIG. 13 3,369,252 2/1968 Adams 101/426 x 3,400,656 9/1968 Thourson.... 101/010. 13

Brodie 1 17/37 LE VOLTAGE 5O U-RCE 22/ CATCHER L 1451 Dec. 17, 1974 3,417,734 12/1968 Simm et al 117/37 LE X 3,515,064 6/1970 Vlier 101/416 A X 3,595,994 7/1971 Whitman... 346/75 X 3,596,275 7/1971 Sweet 346/75 3,681.778 8/1972 Keur 346/75 OTHER PUBLICATIONS IBM Ink Jet Deflection Plate Arrangement" Techn. Discl. Bulletin, Vol. 15, NO. 2, July, 1972.

Misting of Inks" American Ink Maker, May, 1964, I

Primary ExaminerRobert E. Pulfrey Assistant Examiner--13. I-I. Eickholt Attorney, Agent, or Firm-Lindenberg, Freilich', I

Wasserman, Rosen & Fernandez [5 7 ABSTRACT In an ink drop printer; an impacting drop may cause spatter which acts as a fog settling over various parts of the machine and printer media. The drops are maintained intact by directing a flow Of gas to intercept only the terminating portion of the path of said ink drops just prior to and at the time Of impacting upon a region of paper and to cover the region of said paper upon which the ink drops fall, whereby the deleterious effects of spatter may be eliminated.

6 Claims, 3 Drawing Figures WASTE when read. in

- 1 I METHOD AND MEANS FOR OPERATING AN INK JET PRINTER WITHOUT SPLATTER BACKGROUND OF THE INVENTION The present invention relates to ink drop printing apparatus and, more particularly, to an arrangement for eliminating ink drop spatter.

. machine and on the paper.

In ink drop printers, drops are formed from an ink jet which has enough velocity to project the drop a distance through a drop charging ring thereafter, between deflection plates','finally, landing on the paper on which the printing is to occur. The collision between the ink I drop and the paper is not entirely inelastic. Some of the kinetic energy of the fluid is retained, and not all of it is converted to heat. This energy manifests itself in eddy currents within the impacting drop. If these eddies are of a high enough energy and have not been dissipated by viscous forces within the drop, they may escape the fluid gas interface, breaking through the surface tension barrier of the drop.

Referring now to FIG. 1, there maybe seen a side and enlarged view of the region at the end of the drop trajectory. There maybe seen the ends of the deflection electrode, respectively 10, 12, which are biased by a voltage source 14, to establish an electric field therebetween-Drops which are formed by the ink drop mechanism, not shown, and charged or not, in accordance with the dictates of the data to be written, are projected through these electrodes. The uncharged drops, exem- This escape fluid' is in the formiofatomized droplets I which act as a fog, settling over the various parts of the machine and on the printing media. They may also be charged particles which are attracted orrepelled by electric chargesThus, this ink fog lIOt' only may discolor the printing somewhat; but also can cause electrical problems. i ,v I V OBJECTS AND SUMMARY OF THE INVENTION An object of this invention is the provision of an ink jet printer without spatter. 1 I Another object of this invention is to improve the appearance of printing of anink jet printer. These and. other objects of the invention may be achieved by eitherv insuring that the ink drop which lands on the paper does not spatter, using airflow to maintain the ink drops intact or, using airflow and a porous capture electrode'removing any fog that may have been formed as a result of splatter.

'The novel features of the invention are set forth with particularity'in theappended claims. The invention will best be understood from the following .description conjunction with the-accompanyin'gdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS F IG; 1 illustrates drops impacting on.pape r from an ink jetprinter, andfurther shows an embodiment of the invention.

FIG. 2 shows'dropsimpacting on paper, and illus trates a second embodiment of the invention.

FIG. 3 schematically-shows drops impacting on paper, and illustrates still another embodiment of the invention. I v 1 v t j DESCRIPTION TI-IE PREFERRED v EMBODIMENTS I Inkdrop printers are .wellknown and are illustrated for'example, in US. Pat. No. 3,631,511. An ink drop is projected with enough velocity toward the paper on which it will 'finallycome to rest, to bridge the distance between the location at which itis formed and charged, the distance throughthe deflecting electric field, and then thereafter landing on-thepapen-As pointed out currents within the impacting drop are greater than the plified by drops 16, 18, strike a deflector 20, and there after, are deflected into a waste catcher 22. Drops which were charged, exemplified by drops24, 26, and 28, are deflected so that they are deposited, on paper 30, in a pattern to represent a character or symbol, depending upon data which is to be printed. As previously indicated, the impacting drops can spatter.

In accordance with this invention, one 'way in which spatter can be eliminated is to provide for a sufficient gasflow or airflow normal, or as near normal, to the document as can be achieved without disturbingthe f1- delity of the printing. This airflow has the effect of suppressing fluid particles at the impacted drop position. In order to achieve this airflow, a blower 32 is employed which has a guide duct 34, which emits what may be called a beam of gas which has a sufficient cross sectional area to impact the entire printing area. That is, if the ink drop printer is of the type wherein the makes an angle of approximately l 5 with an axis nor- I mal to the document, there is a minimum'interference a with the drop trajectory. For drops impacting at 800 ips (inches per second), effective gas velocities which are i of an ink drop writing machine, illustrating the drops I employed are in the range of 400 to 600 ips. Higher drop velocities require higher gas velocities.

FIG. 2 also is a schematic illustration of the portion passing through the end of the deflection electrode and landing on the paper, and also illustrating another embodiment of this invention whereby spatter maybe eliminated. Parts of the structure which function in similar manner as they did in FIG. 1 have the same reference numerals as in FIG. 1.

In place of directing a gasflow at the drops to sup press spatter, a vacuum source 40 is employed. Paper, has-a certain degree of porosity so that the vacuum ap? plied to the back of the paper 30, employing avacuum source 40, will cause the drops to remain intact and not spatter. The vacuum source 40 applies a vacuum by means of aduct42, to theregionof the paper 30 at which printing occurs. A porous plate 44, supports the previously, spatter occurs when the energy of the eddy and is maintained flat. i y

If desired, both the blowing and vacuum technique may be applied which has the effect of reducing the required blown gas velocity as well as the required vacuum. I

FIG. 3 shows again, the structure adjacent the paper I on which the ink drop impacts for the purpose of illustrating another embodiment of the invention. Here, at one side of the paper, adjacent tothe region at which the drops impact, there is provided a porous electrode 46 to which a voltage is applied by means of a voltage source 48, to bias the porous electrode to a potential which is opposite to the potential of the charge which is'applied to the drops. The porous electrodeis positioned in the path of a vacuum, from a vacuum source 50.

The charged porous electrode attracts opposite polarity droplets which may be created as a result of the spatter which can occur when a drop strikes or falls upon the paper. The vacuum source creates a gentle current of air which effectively directs the fog or droplets caused by the spatter toward the region of the porous electrode. Because of thecharge on the porous electrode, the drops are then directly attracted thereto.

Thus, an efficient collection of the ink fog or spatter is achieved withthis embodiment of the invention.

There has accordingly. been shown and described above, novel and useful arrangements for eliminating the effects of. spatter in ink dropprinters.

Whatis claimed is:

l. In an ink drop printer of the type wherein charged drops are projected by means through air, through a deflecting electric field toward paper, located beyond said deflecting electric field, to fall thereon at a location determined in accordance with the reaction between their charge and the electric field,

.means for eliminating the effects of spatter caused by said drops impacting on said paper comprising: means for directing a flow of gas to intercept only the terminating portion of the pathof said ink drops just prior to and at the time of impacting upon said region of said paper and to cover the region of said paper upon which said ink'drops fall, for maintaining said dr'ops intact. 5

.2. in an ink drop printer as recited in claim 1 wherein blower means for. generating a beam of gas having a cross-sectional area sufficiently large to cover the region on said paper upon which said ink drops fall; and

means for directing said beam of gas at an angle with the normal to said paper which provides a minimum of interference with the drop trajectory.

3. In an ink drop printer as recited in claim 2 wherein said angle made by said beam of gas with the normal to said paper is on the order of 15.

4. In an ink drop printer as recited in claim I further comprising:

means for directing a vacuum at the rear of said paper behind the region of said paper upon which said ink drops fall for maintaining said impacting ink drops intact.

5. In an ink drop printer as recited in claim 4 wherein there is included a porous plate means for supporting the region of said paper, at the rear thereof, to which said means for applying a vacuum applies said vacuum.

6. In an ink drop printer of the type wherein charged drops are projected by means through air, through a deflecting electric field toward paper located beyond said deflecting field to fall thereon at a location determined in accordance with the reaction between their charge and the electric field,

V the method of maintaining the drops'intect at the location where said drops impact on said paper comprising:

directing a flow of gas at the region of said paper upon which said ink-drops fall fromone side of the path of said ink drops toward said paper, at an angle which intercepts the path of said ink drops just prior to and at the time of impacting upon said region of said paper. 

1. In an ink drop printer of the type wherein charged drops are projected by means through air, through a deflecting electric field toward paper, located beyond said deflecting electric field, to fall thereon at a location determined in accordance with the reaction between their charge and the electric field, means for eliminating the effects of spatter caused by said drops impacting on said paper comprising: means for directing a flow of gas to intercept only the terminating portion of the path of said ink drops just prior to and at the time of impacting upon said region of said paper and to cover the region of said paper upon which said ink drops fall, for maintaining said drops intact.
 2. In an ink drop printer as recited in claim 1 wherein said means for directing said flow of gas at the region of said paper upon which said ink drops fall comprises: blower means for generating a beam of gas having a cross-sectional area sufficiently large to cover the region on said paper upon which said ink drops fall; and means for directing said beam of gas at an angle with the normal to said paper which provides a minimum of interference with the drop trajectory.
 3. In an ink drop printer as recited in claim 2 wherein said angle made by said beam of gas with the normal to said paper is on the order of 15*.
 4. In an ink drop printer as recited in claim 1 further comprising: means for directing a vacuum at the rear of said paper behind the region of said paper upon which said ink drops fall for maintaining said impacting ink drops intact.
 5. In an ink drop printer as recited in claim 4 wherein there is included a porous plate means for supporting the region of said paper, at the rear thereof, to which said means for applying a vacuum applies said vacuum.
 6. In an ink drop printer of the type wherein charged drops are projected by means through air, through a deflecting electric field toward paper located beyond said deflecting field to fall thereon at a location determined in accordance with the reaction between their charge and the electric field, the method of maintaining the drops intect at the location where said drops impact on said paper comprising: directing a flow of gas at the region of said paper upon which said ink drops fall from one side of the path of said ink drops toward said paper, at an angle which intercepts the path of said ink drops just prior to and at the time of impacting upon said region of said paper. 